impeller.net The Online Pump Magazine

22.09.2003

Number of Pole Pairs

The number of pole pairs determines the synchronous speed of the three phase motor.


nsync = synchronous speed
f = frequency of the 3-phase power supply
p = number of pole pairs of the 3-phase motor

Kindly note that the above noted relation results in revs per second if the frequency unit is Hz.


Pole pair numbers123456
Synchronous speed (at 50 Hz) n [rpm]300015001000750600500
Synchronous speed (at 60 Hz) n [rpm]360018001200900720600


The rated full-load speed of three phase asynchronous motors is, due to slip, a few percent below the synchronous speed.





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